After slaying the Nemean lion, Eurystheus sent Heracles to slay the Hydra, which Hera had raised just to slay Heracles. Upon reaching the swamp near Lake Lerna, where the Hydra dwelt, Heracles covered his mouth and nose with a cloth to protect himself from the poisonous fumes. He fired flaming arrows into hydra’s lair, the spring of Amymone, a deep cave that it only came out of to terrorize neighboring villages. He then confronted hydra, wielding a harvesting sickle (according to some early vase-paintings), a sword or his famed club. The weakness of the Hydra was that only one of its heads was immortal.

This is the menacing ﻿﻿﻿FlaKturm VII G-Tower (FlaKtower). Built in 1942 ﻿it was armed with 8 AA 128mm Guns 32 20mm AA guns.
These bunkers were virtually 20th century citadels where up to 20,000 people could seek shelter during bombings.